Bearing arrangement for a shaft of a pump drive

Abstract

Bearing arrangement for a shaft (12) of a pump drive, comprising a housing with a housing part (14) made of light metal and penetrated by the shaft (12), the bearing arrangement comprising a sleeve (18) made of steel which is held on the housing part (14) by a positive locking anti-rotation device (32, 36) and comprising a rolling bearing for the shaft (12) and a freewheel (28; 28') arranged axially offset to the rolling bearing for blocking rotation of the shaft (12) in one direction of rotation, wherein the freewheel (28) has clamping pins (42) which roll on the circumferential surface of the shaft (12), characterized in that - the sleeve (18) is a stepped sleeve, with a part (20) with an increased diameter adjacent to the housing part (14) made of light metal for receiving the rolling bearing and a part (26) with a reduced diameter adjoining it via a step (24) for receiving the freewheel (28; 28'), and - that the rolling bearing is a deep groove ball bearing (22) with an inner ring (50) held on the shaft (12) by press fit and an outer ring (48) held in the sleeve (18), which is axially supported on the step (24) of the sleeve (18).

Description

[0001] The invention relates to a bearing arrangement for a shaft of a pump drive, which has a housing with a housing part made of light metal and through which the shaft passes, which bearing arrangement has a sleeve made of steel which is held on the housing part by a positive locking anti-rotation device and has a rolling bearing for the shaft as well as a freewheel arranged axially offset to the rolling bearing for blocking rotation of the shaft in one direction of rotation, wherein the freewheel has clamping pins which roll on the circumferential surface of the shaft as well as a hardened outer ring which is held in the sleeve in a press fit.

[0002] From DE 10 2018 221 829 A1, a bearing arrangement for an output shaft of an electric motor is known, which drives an oil pump of a motor vehicle via a planetary gear. Since the freewheel integrated into the bearing arrangement only allows rotation of the sun gear of the planetary gear in one direction, the oil pump can alternatively also be driven directly by the vehicle's internal combustion engine via the ring gear of the planetary gear. Because the sleeve that accommodates the rolling bearing and the freewheel is made of steel and is held against the housing part, which is made of a softer material, by the anti-rotation device, a high torque can be absorbed in the direction in which the freewheel locks. Since the freewheel and the rolling bearing do not require an inner ring, the bearing arrangement requires very little installation space.However, when pressing the shaft axially into the freewheel and the rolling bearing, it should be rotated around its longitudinal axis to avoid uneven wear on the clamping needles of the freewheel and on the rolling elements of the rolling bearing.

[0003] The object of the invention is to create a bearing arrangement with a simple and compact design that is capable of absorbing higher axial forces.

[0004] This problem is solved according to the invention by the fact that - the sleeve is a stepped sleeve, with a diameter-enlarged part adjacent to the light metal housing part for receiving the rolling bearing and a diameter-reduced part adjoining it via a step for receiving the freewheel, and - that the rolling bearing is a deep groove ball bearing, with an inner ring held on the shaft by a press fit and an outer ring held in the sleeve, which is axially supported on the step of the sleeve.

[0005] Since the rolling bearing is a deep groove ball bearing, it can absorb higher axial forces acting on the shaft, particularly in the direction where the outer ring of the rolling bearing rests against the shoulder of the stepped sleeve. Because the deep groove ball bearing necessarily has an inner ring, a slightly larger installation space is required in the radial direction. However, since the part of the stepped sleeve that accommodates the deep groove ball bearing is directly adjacent to the light-alloy housing part, which must have a larger diameter than the stepped sleeve anyway, the installation space required for the enlarged diameter of the stepped sleeve is generally already available, without imposing any particular restrictions on the design of the mounting location for the bearing arrangement.The larger radial dimensions of the stepped sleeve also offer the advantage that the anti-rotation device can act over a longer lever arm and therefore withstand higher torques. Since the inner ring of the deep groove ball bearing can be pressed onto the shaft's circumferential surface with high force without increased local wear during the pressing-in process, it can be ensured that the shaft does not shift relative to the bearing assembly, even under the influence of high axial forces.

[0006] The following section explains an exemplary embodiment in more detail with reference to the drawings.

[0007] They show: Fig. 1 a bearing arrangement according to the invention in an axial section; Fig. 2 a view of the bearing arrangement from the direction of arrows II-II in Fig. 1; and Fig. 3. a bearing arrangement according to another embodiment.

[0008] The in Fig. The bearing arrangement 10 shown in Figure 1 serves to support a shaft 12, which may, for example, be an output shaft of an electric motor. The electric motor is located in Fig. Figure 1 shows only a housing part 14 made of die-cast aluminum, which accommodates the rotor and the stator of the electric motor and has an end wall 16 to which a sleeve 18 of the bearing assembly is rigidly attached. The sleeve 18 is a deep-drawn steel part in the form of a stepped sleeve, with a diameter-enlarged part 20 adjacent to the housing part 14, which accommodates a rolling bearing 22, and a diameter-reduced part 26 adjoining it via a step 24 for accommodating a freewheel 28.

[0009] At the free end of the diameter-expanded section 20, the sleeve 18 forms a radially outwardly extending flange 30, which rests against the end wall 16 and is held rotationally fixed to the housing part 14 by an anti-rotation device. Part of the anti-rotation device is formed by pins 32, which extend from the end wall 16 of the housing part 14 and are received with almost no play in corresponding notches in the edge of the flange 30. As shown in Fig. As shown in Figure 2, a further part of the anti-rotation device is formed by two flattened surfaces 34 on the edge of the flange 30, against which ribs 36 projecting from the end wall 16 bear.

[0010] At the free end of the reduced-diameter part 26, the sleeve 18 forms a flange 38 which extends radially inwards and surrounds the shaft 12 at a small distance.

[0011] The freewheel 28 has an outer ring 40 and a ring of clamping pins 42, which are held in a cage 44 and roll directly on the circumferential surface of the shaft 12. The outer ring 40 forms a clamping contour for the clamping pins 42 (not visible in the drawing) and has a radially inwardly extending flange 46 at its end facing the rolling bearing 22. The outer ring 40 is press-fitted in the reduced-diameter section 26 of the sleeve 18. When a torque acts on the shaft 12 in the direction in which the freewheel 28 locks, this torque is positively transmitted from the outer ring 40 of the freewheel to the sleeve 18 and further via the flange 30 and the anti-rotation device, i.e., the pins 32 and the ribs 36, to the housing part 14.Conversely, the housing part 14 exerts a counter-torque on the shaft 12 via the sleeve 18 and the freewheel, so that the shaft is prevented from rotating in the blocking direction of the freewheel relative to the housing part 14.

[0012] The deep groove ball bearing 22 has an outer ring 48, an inner ring 50, and a ring of bearing balls 52, which are held in a cage 54 and run in grooves of the inner and outer rings. The outer ring 48 is press-fitted in the diameter-enlarged part 20 of the sleeve 18 and is supported axially by a shoulder of the sleeve 18 formed by the step 24. In the fully assembled state, the inner ring 50 is press-fitted onto the shaft 12. Fig. Figure 1 shows shaft 12 in a state during a press-fitting process for clarity, in which the shaft is separated from the Fig. 1. The right side is pressed into the freewheel 28 and the inner ring 50 of the deep groove ball bearing 22 and then finally into the stator of the motor. To prevent local wear of the clamping pins 42 during this pressing process, the shaft 12 should be rotated about its longitudinal axis during the pressing process. If, as in Fig. As shown in Figure 1, when the end of the shaft 12 enters the inner ring 50 of the deep groove ball bearing, the inner ring 50 can rotate with the shaft 12, so that during the pressing-in process the relative movement between shaft 12 and inner ring 50 is a purely axial movement, which allows the production of a press fit with high frictional engagement between the shaft 12 and the inner ring 50.

[0013] In another embodiment, the shaft 12 can be rigidly connected to the motor rotor before the bearing assembly 10 is mounted. In this case, the bearing assembly with the deep groove ball bearing 22, the freewheel 28 and the sleeve 18 is attached to the rotor by the shaft 12. Fig. 1. The shaft is pressed onto the shaft from the right side. This has the additional advantage that the shaft is precisely centered when pressed into the inner ring 50 of the deep groove ball bearing, so that damage to the clamping pins 22 can be reliably avoided when further pressing into the freewheel 28 (again with slight rotation).

[0014] If shaft 12 is subjected to axial forces acting in the right-hand direction after assembly is complete Fig. When forces act, they are transmitted via the high frictional contact to the inner ring 50, and then further via positive locking to the outer ring 48, and finally to the shoulder of the sleeve 18. Since this sleeve 18 is rigidly attached to the housing part 14, axial movement of the shaft 12 is reliably prevented.

[0015] Fig. Figure 3 shows a modified embodiment in which the sleeve 18 is made of stainless steel and directly forms the outer ring of a freewheel 28'. Accordingly, the reduced-diameter portion 26 of the sleeve 18 has a clamping contour for the clamping pins 42. This clamping contour can be produced during the deep drawing of the sleeve 18. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 221 829 A1

[0002]

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